Manufacturing or packaging line employees in the prepared-foods, agri-food stuffs, and pharmaceuticals industries are generally required to wear sealed gloves for hygiene purposes. The gloves used for these purposes are usually white or of a light flesh color. During the course of manufacturing or packaging, small pieces of the glove may become torn off or separated from the glove. The small pieces of glove may become contaminants in the food or pharmaceutical product being handled. The white or light flesh-colored glove pieces are often difficult to discern from the product and, therefore, become very difficult to remove prior to packaging and shipping the product.
Detecting glove pieces may be solved by use of gloves of a color that distinctively contrasts the color of the product. However, reliance upon visual detection alone leaves room for human error and missed contaminants may be packaged with the product.
Flexible polymers or magnets containing an amount of magnetically detectable ferrite have been known since the 1960s. A glove containing ferrite for purposes of rendering the glove magnetically detectable has been described. The polymeric materials that have ferrite added as fillers will be either dark red or black in color depending upon the oxidation state of the iron in the ferrite. The use of red or black colored gloves for use in the preparation of food or pharmaceutical products may be objectionable in some applications.
Chrome oxides are known for their magnetic properties. Specifically, chromium (IV) oxide, or CrO2, and chromium (III) oxide, or Cr2O3, possess magnetic properties. Chromium (III) oxide has a molar susceptibility of +1960, which is calculated based on the magnetic field, the magnetization (magnetic moment per unit volume), the molar volume of the substance, the molar mass, and the mass density. CRC Handbook of Chemistry & Physics, David R. Lide, Magnetic Susceptibility of the Elements and Inorganic Compounds, p. 4-132. Chromium (VI) oxide has magnetic properties, but to a much lesser degree, with a molar susceptibility of +40. Id. Chromium (IV) oxide is more magnetic than chromium (VI) oxide and is commonly used in magnetic media, in which needle-shaped particles of CrO2 are used to create a magnetic surface for videotapes and audiotapes. The use of chromium oxide compounds in polymeric films is known in the recording tape industry. Magnetic tapes containing CrO2 have been widely used since the 1970s. Chromium oxide such as CrO2 has also been used in films containing magnetically oriented pigment. Chromium oxide in the form of Cr2O3 is olive green in color. Chromium oxide in the form of CrO2 is black in color.
U.S. Pat. No. 5,467,481 describes protective gloves that color the hands of the wearer for purposes of reminding the wearer to wash after removing the gloves. Chromium oxide in the form of Cr2O3 is used as a preferred colorant, but is not contained within polymer layers of the glove, rather the chromium oxide is a powder that coats the interior of the glove. The pigmented glove, however, was not used for its magnetic property.
U.S. Pat. No. 5,019,453 describes a protective material that includes a layer of vinylidene chloride, or a copolymer of vinylidene, between two layers of polyethylene to provide protection against permeation and breakthrough. One or more of the layers may be treated with a strong oxidant, and the oxidant may be chromium trioxide. However, the chromium trioxide is not incorporated and dispersed throughout the polymer and was only used to oxidize a layer in preparation for lamination.
Additionally, metal oxide-containing fibers, fabrics, clothes and shoes are known. The metal oxides are purported to have a therapeutic effect on the wearer of these items. For example, in U.S. Pat. No. 6,120,531 a metal oxide substance contained in the fibers, fabric or clothing may include substances containing up to 96% chromium oxide. However, chromium oxide was chosen for its reflective properties rather than for its magnetic properties. When stimulated by the body heat of the wearer, the metal oxide material in the fabric or clothing reflects the heat to an area required for a particular therapeutic purpose.
There is a need, therefore, for magnetically detectable latex articles such as gloves. There is also a need for latex articles such as gloves having magnetic properties such that pieces of the latex article or glove may be detected by a magnet.